1. Field of the Invention
The present invention relates to a radiation detecting apparatus including a conversion element converting a radiation or a light into electric carriers, and a thin film transistor (TFT) being a switching element in a pixel.
The radiation detecting apparatus is especially suitably used for a radiation detecting apparatus detecting a radiation, and is used for a medical diagnostic apparatus, a nondestructive inspection apparatus, an analysis apparatus using a radiation, and the like. Hereupon, in the present specification, it is supposed that visible light or like, not only an α-ray, a β-ray, a γ-ray and the like, which are beams produced by particles (including photons) emitted by radioactive decay, but also beams having the energy of the same degree of intensity as those of the particles such as an X-ray, a corpuscular ray, a cosmic ray and the like are included in a radiation.
2. Description of Related Art
Recently, enlargement in size of a TFT matrix panel, in which are formed on an insulating substrate, and the speeding up of the drive speed of the TFT matrix panel have been being rapidly advanced. The manufacturing techniques of a liquid crystal panel using are used for an area sensor (for instance, a radiation detecting apparatus) including semiconductor conversion elements each converting a radiation such as an X-ray into an electric signal. As such a semiconductor conversion element, for instance, there are a semiconductor conversion element arranging an wavelength converting layer (for instance, a phosphor layer) performing the wavelength conversion from a radiation such as an X-ray into a light such as a visible light on the surface of the semiconductor conversion element to perform the photoelectric conversion of the light, a semiconductor conversion element using a semiconductor converting material performing direct conversion of a radiation into an electric signal, and the like.
On a substrate arranging thereon such semiconductor conversion elements and TFTs for reading the electric signals from the semiconductor conversion elements two-dimensionally to read a quantity of radiation irradiation, the quantity of the radiation irradiated to each pixel or the quantity of the light converted from the radiation are detected. Although it is possible to provide a highly sensitive radiation detecting apparatus by detecting the quantities more, it is necessary for the sake that the semiconductor conversion elements are arranged by using the whole space effectively while the performances of the TFTs are kept.
Accordingly, in prior art, there has been a proposal in which, after a TFT array has been formed, the semiconductor conversion elements are laminated on the TFT array to prevent the losses of the aperture ratios by the TFTs and to improve sensitivity. As an example thereof, Japanese Patent Application Laid-Open No. 2004-15002 describes that semiconductor conversion elements are arranged above TFTs.
A planarization layer is formed on the source electrode and the drain electrode of a TFT, and a semiconductor conversion element is formed above the planarization layer. The provision of the planarization layer reduces the capacitive coupling between the TFT and the semiconductor conversion element, and consequently it becomes possible to form the semiconductor conversion element on the TFT and each wiring. By adopting such a configuration, the aperture ratio of the semiconductor conversion element is improved.